Duplexers using acoustic wave elements are small in size and have high steepness, and thus have been widely used in wireless terminals such as mobile phones. The wireless terminal receives interfering wave signals with frequencies different from the frequency of a reception signal in addition to the reception signal. There has been known that non-linear effect of a resonator including an acoustic wave element causes intermodulation distortion (IMD: Intermoduration Distortion), and degrades receiving sensitivity. There has been known a circuit configuration dividing a series resonator in a duplexer and connecting them to reduce the above described non-linear characteristics, for example (e.g. Japanese Patent Application Publication No. 2010-21914).
When a series resonator is divided and connected in a duplexer, a layout area of the resonator becomes large, and may prevent downsizing.